Doesn't want to accelerate past ~6Krpm Need help please

How to keep your little baby running smoothly.

Doesn't want to accelerate past ~6Krpm Need help please

Postby Kasper » Sat Jul 06, 2013 8:59 pm

Hello I'm having some trouble with my 89vtr. After it sat for a winter + a few months, I replaced spark plugs, oil and filter. I used the recommended ngk's as well as the recommended oil filter. Shortly after that(less then a week of mild use) the bike started to bog down when the rpms would reach about 6.5k rpms. I tested both spark plugs they are working fine. Tried new fresh gas. (89oct) I am thinking it probably has something to do with carb tuning, but Ive never tuned the carbs before so I wanted to see if it could possibly be something else before I messed with the carbs because it worked fine last season. If anyone could help out I would greatly appreciate it.
Kasper
 
Posts: 4
Joined: Sat Jul 06, 2013 8:46 pm

Re: Doesn't want to accelerate past ~6Krpm Need help please

Postby XRayHound » Sat Jul 06, 2013 9:54 pm

Carbs need to be cleaned before anything else if you let it sit for a year.
XRayHound
 
Posts: 546
Joined: Sun Jul 22, 2012 4:31 pm

Re: Doesn't want to accelerate past ~6Krpm Need help please

Postby cawalther » Sat Jul 06, 2013 10:17 pm

Does it idle / run at an idle? I might get flamed for this.. but if it is running at an idle fine, i would try starting it up, revving it up to that 6k range and then spray some carb cleaner up at the airbox intake snorkel and see if it will rev past that 6k range. It will die back down if it does and this will not clean your main jet if that is what's clogged. It will give you a general sense of whether or not it is carb related or if it is ignition related. The magneto pick ups can go bad or it could be CDI related.

so if it revs up then your ignition system is in check and you need to assess the carb(s)
if it does not rev with added "safe" combustibles, then it is ignition related and may bog down a bit since the A/F will be richer.
Walth
89 VTR 250 (since '07)
06 DR650se (since April '15)
User avatar
cawalther
Moderator
 
Posts: 357
Joined: Sun Aug 26, 2012 2:20 pm
Location: Central Virginia, USA

Re: Doesn't want to accelerate past ~6Krpm Need help please

Postby John Hilmer » Sun Jul 07, 2013 5:03 am

The principle above is fine, but don't use carb cleaner or starting fluid which can ruin the diaphragms.

John
Lord help me to be the man my Labrador thought I was.
It's never too late to have a happy childhood ...
John Hilmer
Moderator
 
Posts: 1980
Joined: Tue Jun 05, 2012 7:29 am
Location: Scotts Valley, Ca.

Re: Doesn't want to accelerate past ~6Krpm Need help please

Postby cawalther » Sun Jul 07, 2013 5:15 am

The carb diaphragms? Yeah, it is a possibility. I just don't have any other alternatives.. Except for MAF cleaner, ultra quick evaporation..
Walth
89 VTR 250 (since '07)
06 DR650se (since April '15)
User avatar
cawalther
Moderator
 
Posts: 357
Joined: Sun Aug 26, 2012 2:20 pm
Location: Central Virginia, USA

Re: Doesn't want to accelerate past ~6Krpm Need help please

Postby John Hilmer » Sun Jul 07, 2013 5:22 am

Chris,

Even WD-40 will work for the test you propose. So will an unlit propane torch.

John
Lord help me to be the man my Labrador thought I was.
It's never too late to have a happy childhood ...
John Hilmer
Moderator
 
Posts: 1980
Joined: Tue Jun 05, 2012 7:29 am
Location: Scotts Valley, Ca.

Re: Doesn't want to accelerate past ~6Krpm Need help please

Postby cawalther » Sun Jul 07, 2013 5:32 am

Interesting options.. I did not think wd-40 was flammable flash point wise like fuel.

I was just thinking about it, run to a dollar store and get a cheap spray bottle like for cleaning or haircuts, etc. I wouldn't spray stream wise but a slight mist. The vacuum will draw it into the air box. Just spray 2-4 pumps.. If nothing happens then back off the throttle and test again and see if the idle raises on its own with the same number of pumps.

use fuel and when you're done just pour the excess back into your gas container or fuel tank and let it air dry and keep it clean and mark it for garage/fuel use only
Walth
89 VTR 250 (since '07)
06 DR650se (since April '15)
User avatar
cawalther
Moderator
 
Posts: 357
Joined: Sun Aug 26, 2012 2:20 pm
Location: Central Virginia, USA

Re: Doesn't want to accelerate past ~6Krpm Need help please

Postby John Hilmer » Sun Jul 07, 2013 6:36 am

Chris,

I wouldn't use gas.

You could wind up with a roasted hand.

Brake cleaner is OK in a pinch, but an unlit propane torch is probably the safest.

Back fires are not good.

John
Lord help me to be the man my Labrador thought I was.
It's never too late to have a happy childhood ...
John Hilmer
Moderator
 
Posts: 1980
Joined: Tue Jun 05, 2012 7:29 am
Location: Scotts Valley, Ca.

Re: Doesn't want to accelerate past ~6Krpm Need help please

Postby cawalther » Sun Jul 07, 2013 6:45 am

oh yeah. ha, forgot about backfires. sorry guys. I had my coffee, just after.. I wrote that..

Looking forward to the outcome Kasper. Keep us informed ;)
Walth
89 VTR 250 (since '07)
06 DR650se (since April '15)
User avatar
cawalther
Moderator
 
Posts: 357
Joined: Sun Aug 26, 2012 2:20 pm
Location: Central Virginia, USA

Re: Doesn't want to accelerate past ~6Krpm Need help please

Postby CBXSTAN » Sun Jul 07, 2013 10:56 am

2-7k rpm is controlled by the needle. With the air cleaner off, start the bike and see if the slides move when you blip the throttle. If they are not moving, the slides may be stuck sitting over the season, or the diaphragms damaged.
The slides and diaphragms can be serviced with the carbs on.

If they are moving as they should. Carbs need to come off for a cleaning.
The main jets are likely clogged, the fuel screens under the float seat are plugged, and/or the floats stuck.

There are lots of good write ups on carb cleaning. It is not difficult. Just take your time.
CBXSTAN
 
Posts: 6
Joined: Mon Nov 19, 2012 8:50 pm

Next

Return to Maintenance/Minor Repairs

Who is online

Users browsing this forum: No registered users and 1 guest

cron